Glossary of arachnology terms

This glossary describes the terms used in the formal descriptions of arachnids, particularly spiders.

Terms

• Apophysis: a process or outgrowth of the exoskeleton from any part of the body, but particularly on the appendages

Head and body

• Abdomen or opisthosoma: One of two body segments, towards the posterior end.
• Carapace: The upper (dorsal) portion of the cephalothorax.
• Cephalothorax or prosoma: One of two body segments, towards the anterior end.
• Chelicera: The appendage that includes the fang. (Sometimes called the jaw.)
• Clypeus: the area of the carapace between the anterior eyes and the anterior edge of the carapace.
• Dorsum: The upper (dorsal) portion of the body or abdomen.
• Dorsal groove: Another name for the fovea of the carapace.^[1]
• Fovea: A depression or pit in the centre of the carapace of a spider marking an inward projection of the exoskeleton to which stomach muscles are attached.^[2]
• Labio-sternum mound: A mound separating the labium from the sternum, found in found in some tarantulas, where it can be a diagnostic feature.^[3]
• Sternum: The lower (ventral) portion of the cephalothorax.
• Thoracic furrow: Another name for the fovea of the carapace.^[4]
• Venter (or ventrum): The lower (ventral) portion of the body or abdomen.

Legs and palps

• Segments:
  • Coxa : first leg segment, between body and trochanter.
  • Trochanter : second leg segment, between coxa and femur
  • Femur : third leg segment, between trochanter and tibia.
  • Patella: fourth leg segment, between femur and tibia.
  • Tibia : fifth leg segment, between patella and metatarsus.
  • Metatarsus (or basitarsus): sixth leg segment, between tibia and tarsus; absent in the pedipalp.
  • Tarsus (or telotarsus): seventh (last) leg segment, after the metatarsus.
• Lateral (applied to legs): viewed from above or below, the sides of the leg or palp, i.e. the surfaces parallel to the line of sight
• Prolateral: viewed from above or below, the side of the leg or palp nearest the mouth, i.e. the side facing forward
• Retrolateral: viewed from above or below, the side of the leg or palp furthest from the mouth, i.e. the side facing backwards

Pedipalp

• Maxilla: modified coxa of the pedipalp, used in feeding.
• Carpoblem: the principal tibial apophysis on the male pedipalp. (Typically, this is just called the tibial apophysis.)
• Retrolateral tibial apophysis: a backward-facing projection on the tibia of the male pedipalp.

Markings

Larinioides cornutus spider showing folium on abdomen

• Folium : A broad leaf-like marking along the medial line of the top of the abdomen.
• Heart mark : A narrow marking along the top of the abdomen roughly corresponding to the location of the heart.

Abbreviations

Some abbreviations commonly found in descriptions of spider anatomy include:

• ALE: anterior lateral eyes
• ALS: anterior lateral spinnerets
• AME: anterior median eyes
• DTA: dorsal tegular apophysis
• DTiA: dorsal tibial apophysis
• LTA: lateral tegular apophysis
• MOQ: median ocular quadrangle
• PLE: posterior lateral eyes
• PLS: posterior lateral spinnerets
• PME: posterior median eyes
• PMS: posterior median spinnerets
• RCF: retrolateral cymbial fold
• RTA: retrolateral tibial apophysis
• VTA: ventral tegular apophysis
• VTiA: ventral tibial apophysis

See also

• Anatomical terms of location
• Glossary of entomology terms
• Glossary of scientific names

References

1. Foelix 2011, p. 17.
2. Roberts 1995, pp. 13–14.
3. Smith, A. M. (1990). Baboon spiders: Tarantulas of Africa and the Middle East. Fitzgerald Publishing, London, pp. 1-142
4. Foelix 2011, p. 18.

Bibliography

• Foelix, Rainer F. (2011). Biology of Spiders (3rd p/b ed.). Oxford University Press. ISBN 978-0-19-973482-5.
• Comstock, John Henry (1920) [First published 1912]. The Spider Book. Doubleday, Page & Company.
• Roberts, Michael J. (1995). Spiders of Britain & Northern Europe. London: HarperCollins. ISBN 978-0-00-219981-0.